$OpenBSD: patch-Makefile,v 1.8 2016/12/30 13:57:51 sthen Exp $
--- Makefile.orig	Sat Jul 23 20:43:37 2016
+++ Makefile	Sat Dec 17 18:41:07 2016
@@ -81,7 +81,7 @@ else
 OPT = $(POPT)
 endif
 INCLUDE = -Iinclude
-CFLAGS = $(OPT) $(WARN) $(INCLUDE) $(CFLAGS.EXTRA)
+CFLAGS += $(OPT) $(WARN) $(INCLUDE) $(CFLAGS.EXTRA)
 
 all debug: glew.lib glew.bin
 
